Burner system for finely divided fuels



1932, B. M. JOHNSON ET AL BURNER SYSTEM FOR FINELY DIVIDED FUELS 2 Sheets-Sheet Filed Nov. 29, 1926 INVENTORS 1932. B. M. JOHNSON ET AL 1,345,753

BURNER SYSTEM FOR FINELY DIVIDED FUELS Filed Nov. 29, 1926 2 Sheets- Sheet 2 1-: INVENTQORS 424,4 W MW E M {7am 1 M Patented Feb. 16, 1932 pmrao STATES PATENT OFFICE BOYD I. JOHNSON, OI IETUGHEN, NEW JERSEY, AND HENRY P. KIRCENER, OI NIAGARA FALLS, NEW YORK, ABSIGNORS TO THE CARBORUNDUM COMPANY, 01' NIAGARA FALLS, NEW YORK, A CORPORATION OF PENNSYLVANIA BURNER SYSTEM FOR FINELY DIVIDED FUELS Application filed November 29, 1826. Serial No. 151,384.

Figure 1 is a sectional side elevation showing a Cannon furnace provided with our improved burner system;

Figure 2 is a longitudinal section showing referred form'of burner; igures 3 and 4 are cross-sections of the same on the lines of III--III and IV --IV of Figure 2 looking in the direction of the arrows;

Figure 5 is a view similar to Figure 2 showingra modified form; and

igure 6 is a similar view showing still another modification.

Our invention relates to burners emplo ing air and a finely divided fuel, such as pu verized coal; and articularly to such burners where preheated air is supplied to the mixture entering the burner. The object is to provide a simple and effective burner system of this type, and particularly one in which the hitherto long flame projected from the burner is materally shortened. A further object of our invention is to provide an arrangement by which powdered coal may be effectively burned in a radiant type of combustion chamber.

In the drawings, referring to the preferred form of Figures 2, 8 and 4, 2 represents a burner tip aving the general shape of the frustum of a cone, with converging sides, with a-fian e 3 by which it may be bolted or otherwise astened to a burner pipe 4. Projecting inwardly from the wall portions of the tip casing 2 are bars or supports 5 whose inner ends are secured to the outer surface of a conical spreader 6 having its walls diverging with in the convergin walls of the tip, This s reader, in the orm shown, projects into t e incoming fuel stream be ond the end of the tip, and on its outer sur ace is provided with a set of curved vanes 7 extending into pipe 4 and designed to cause a swirl in the fuel and air mixture flowing in contact with them. The pipe portion 1 may be fastened to or form an extension of a supply pipe 8, as shown n Figure 1. In the particular installation 11- lustrated in Figure 1, the burner projects into a radiating combustion unit of the general type disclosed in United States Patents Nos. 1,371,773, 1,371,774 and 1,550,340 to H. B.

Cannon, such unit being formed of a refractorv material, such as one containing silicon carbide, having a high ca acity for absorbmg heat from a flame wit in said unit and radiating this heat to surrounding objects. This combustion unit shown in Figure 1 comprises a combustion passage 9 in which the fuel is burned and beneath this passage another passage or passages 10 through which air is passed, the air passing through the passages 10 being preheated for combustion, the air serving to cool the bottom wall of the passage 9 and prevent it from overheating. In the form shown the air is first heated in a jacket space 11 surrounding a portion of the uptake flue 12, from which jacket space the air enters the lower end of the fiue 10, as shown by the arrows. The air is drawn through this heating flue by a fan 13. This fan discharges into a conduit 14 leading to the burner supply conduit 8, and from it a branch pipe, shown in dotted lines and marked 15, leads a relatively smaller portion of the heated air into the pulverizer 16 supplied with coal from hopper 17 and this air serves to carry the pulverized fuel into the burner. 18 represents a belt drive for the pulverizer, this drive being connected to the fan by belt 19. From the pulverizer an inner pipe 20 leads the mixture of pulverized fuel and air into the rear portion of the burner, this inner pipe preferably terminating at or near the rear end of the cone 6. The conduit 9, including its bottom, is formed of a bonded silicon carbide, which is many times more thermally conductive than ordinary fire clay. Heat is therefore conducted through the bottom of the chamber at a high rate, and the air is very effectively preheated, while the inner surface of the bottom of the combustion flue is protected from overheating. Heat is dissipated from the side walls of the unit by radiation to the relatively cooler surface of the surrounding structure. 21 is a conventional illustration of part of a steam boiler. In the use of this form of the device the air heated in the lower passage 10 is drawn through the fan and a portion of it passes into the pulverizer where it mixes with the pulverized fuel and the mixture passes through the pipe 20.

The larger portion of the heated air is fed desirable in many furnaces, and particularly in a radiating combustion unit because it per- ,15 mitsthe unit to be relatively short and more uniform temperatures along the entire length thereof. If there is a long flame the temperature of the unit at the burner end is relatively low, and the heat highly localized in theilnit 20 at a point remote from the burner. Furthermore, the fuel is brought into more intimate contact with the walls of the unit with the resent type of burner and the catalytic efect of the silicon carbide refractory 1s made more available for promoting combustion.

For a better understanding of our invention we refer to Mellors Inorganic and Theoretical Chemistry, Vol. V, page 881,-wherem in Wologdine is quoted as obtaining for the thermal conductivity of silicon carbide brick at 1000 C. 0.0231 calories/cm /G/sec. and for clay bricks 0.0042 in the same units at the same temperature.

In Figure 5 the fuel and air pipe is shown as an inner straight pipeavlng the surrounding curved vanes 7 a In this case the coal and air mixture travels in straight lines to the burner tip 2, and the preheated air is given a rotary motion by means of the vanes before it joins the straight m1xture. Here the preheated air is deflected inwardly by the burner tip, and being in rotary motion an eflicient mixing is obtained.

- In the form of Figure 6, which also ou tlined in Figure 1, the vanes 7 pro ect withm the tip and have tapered end portlons. The inner pipe 20 containing the coal and air mixture is divergent inside the burner tip, I and as the whirling preheated air converges b0 within the tip an eflicient mixture is given. The vanes may be used either inside or outside of the inner pipe or tip, or both inside and out side; and in this and other forms which may be employed within our invention, eflicient and thorough mixing is obtained and a relatively short'flame of high efiieiency is produced.

The burner system may be used with other types of furnaces, the air and fuel mixture may be heated or not previous to joining the preheated air, changes may be made in the burner construction, and other changes may be made without departing from our inven- 66 tion.

We claim:

' 1. The combination with a radiating combustion chamber having a straight passage therethrough from one end to the other of a powdered coal burner having an outwardly flared inner cone connected with a source of air and powdered coal, and a tapering outer cone connected with the source of air supply, the generating lines of said outer cone intersecting the inner surface of the radiating combustion chamber at a point adjacent the mouth of the burner, whereby a relativelyshort flame is produced, and means outside the radiating combustion chamber and spaced therefrom adapted to receive and utilize the geat radiated from the said combustion cham- 2. The combination with a radiating combustion chamber having a continuous straight passageway therethrough, of a powdered fuel burner having a flaring inner cone connected with a source of powdered fuel and air, and an outer cone surrounding the inner cone and connected with a source of air supply, the generating linesfof the outer cone intersecting the inner surface of the combustion chamber adjacent the mouth of the burner, and means outside of said combustion chamber spaced therefrom adapted to. receive and utilize the-radiated heat from the combustion chamber.

3. A vaporizing device comprisin in combination, a horizontally disposed oiler, a radiating combustion chamber composed mainly of silicon carbide, a turbulent burner for heating said combustion chamber, said combustion chamber having a terminal portion which encloses the hottest portion of the flames from said burner and which is adjacent to one end of said boiler, said combustion chamber having another terminal portion below the opposite end of said boiler and spaced further below the'boiler than said first terminal portion, a duct connected to the lower end of said combustion chamber through which the burned gases flow up ast said opposite end of the boiler, a duct or pre-heating air for the combustion chamber adjacent said first-mentioned duct, a second duct under the combustion chamber connected with said first duct for preheating air, said turbulent burner being arranged to discharge a burning mixture of preheated fuel and air against the inside surface of the upper end of the combustion chamber, and means for forcing the air preheated in said ducts into the said turbulent burner to preheat the fuel and mix therewith.

4. A'vaporizing devices described in claim 3 in which the duct for the burned gases has a portion extending below the end of the combustion chamber which opens into it to provide an ash pit for slag which flows out of the combustion chamber into said duct.

5. In a furnace, an elongated radiating 130 1345mmv combustion chamber composed principally of silicon carbide, which chamber is inclined from a horizontal position, a turbulent fuel burner at the upper end of the chamber constructed todirect a flame against the walls of the chamber in close proximity to the burner, an ash pit at the lower end of the chamber, an enclosed air circulating passage along the bottom of the chamber for cooling the bottom of the chamber and preheating air circulating therethrough, and means for withdrawing the air which has been preheated at the upper end of the passage and dischar g it into the chamber for supporting 0015i and means outside of said combustion chamber spaced therefrom adapted to receive and utilize the radiated heat from the combustion chamber.

In testimony whereof we have hereunto Set ustion therein, 

